Power transmission



May 16, 1944. w. T. DUNN 2,349,147

POWER TRANSMISSION Y 3 Sheets-Sheet 1 Filed Jan. 26, 1942 .3. C5INVENTOR E naz/Za, 775mm.

0&4? 1h m ATTORNEY May 16, 1944. w. T. DUNN POWER TRANSMISSION FiledJan. 26', 1942 3 Sheets-Sheet 3 INVENTORl K fig/[idw 7.7ann..

ATTORNEYS- Patented May 16, 1944 POWER TRANSMISSION William T. Dunn,

Chrysler Corporation, corporation of Delaware Detroit, Mich., assignorto Highland Park, Mich., a

Application January 26, 1942, Serial No. 428,159

(Cl. i4- 472) 14 Claims.

This invention relates to motor vehicles and refers more particularly topower transmission and control mechanism therefor.

`This application constitutes an improvement over the control system setforth in my Patent No. 2,257,674 of September 30, 1941, andv is acontinuation-in-part of my copending application SerialNo. 407,307 ledAugust 18, 1941.

In certain types of automatic and semi-automatic transmissions such asshown and described in the copending application of Carl A. Neracher et:al., Serial No. 335,310', filed May 15, 1940, by way of example, it ispossible under rather unusual conditions to so manipulate the vehiclethat the transmission becomes locked up in a shift position; also torender the ignition system inoperative at an undesired time. While theaforesaid unusual conditions would not ordinarily occur, it happens thatonce in a while a driver of a vehicle equipped with this type oftransmission system does experience these difficulties and while saidapplication discloses means to release a locked-up transmission and torestore the ignition system it is nevertheless desirable to insureagainst the occurrence of the undesirable difficulties in the firstplace.

It is an object o my invention to provide means for overcoming theaforesaid dii'liculties, my invention operating automatically withoutattention on the part of the driver.

Another object of my invention is to provide means insuring againstundesired grounding of the engine ignition in connection withtransmission systems employing ignition grounding means for momentaryrelief of torque between positively engaging drive control elementswhereby such elements may be readily relatively separated to release adrive'in the transmission. Such systems are especially desirable wherechange in speed ratio drive is to be made while the engine is deliveringpower by releasing the positive drive control elements which may be theelements of a positive clutch.

A further object of my invention is to provide means for preventing atransmission from getting into an undesired locked-up or no-backcondition in which the driver cannot manipulate the transmission. Suchcondition frequently arises in connection with transmissions employingan overrunning clutch in the line of drive and especially when the cartends to roll backwards down hill and the shift lever is set for forwarddrive.

Y Another object of my control means for modifying invention is toprovide the action of transmission control systems under conditionswhere the driver brings the car to a stop with the engine ignitionsystem turned off prematurely. Under such conditions, especially fortransmission systems embodying governor control of electrical solenoidsor other devices, the drive control elements do not properly respond tothe main transmission control and either the speed ratio change does nottake place as desired or the transmission becomes lock-up or theignition grounded or several or all of these undesired conditions arebrought into action at the same time. My invention insures against theoccurrence of these undesired conditions.

A further object of my invention is to provide a transmission systemwherein my control means is in the form of a switch shunted around or inparallel with the ignition switch. Such an arrangement accommodates useof a series-arranged ignition switch, electromagnet, and governor switchand/or kickdown switch. Thus, systems already employing thisseries-arrangement may be readily arranged to include my safety controlWithout modication of the existing wiring system which would bedifficult and inconvenient in practice. Furthermore, with my improvedcontrol system, the transmission is under desired control as soon as theignition switch is closed, rather than being dependent on turning theengine over. Still further my system will accommodate normal functioningof the transmission system even though the shunt switch fails to close.

Further objects and advantages of my invention will be more apparentfromthe following illustrative embodiment thereof, reference being hadto the accompanying drawings in which:

Fig. l is a side elevational view showing a motor vehicle engine andpower transmission equipped with my invention.

Fig. 2 is a longitudinal sectional elevational view through the mainclutching mechanism.

Fig. 3 is a similar view through the change speed transmission.

Fig. 4 is a detail enlarged view of the blocker clutch as seen in Fig.3.

Fig. 5 is a sectional plan view illustrated as a development accordingto line 5-5 of Fig. 4, the automatic clutching sleeve being released.

Fig. 5 is a similar view showing the automatic clutching sleeve in itsintermediate shift position during the drive blocking condition.

Fig. 7 is a similar view showing the automatic clutching sleeve in itscoasting relationship from the Fig. 6 showing, the clutchingsleeve'belng unblocked during coast for its ment.

Fig. 8 is a similar view showing the automatic clutching sleeve in fullclutching engagement.

Fig. 9 is a view similar to Fig. 5 but showing 5 the automatic clutchingsleeve in its other intermediate shift position during the coastblocking condition.

Fig. 10 is a diagrammatic View of the control mechanism for theautomatic clutching sleeve, 10 the latter being shown in its releasedposition.

Fig. 11 is a similar view of a portion of the Fig. l0 control mechanismin another operating position.

While my control may be employed in con- 15 junction with various typesand arrangements of motor vehicle transmissions, in order to illustrateone driving system I have shown my invention in connection with certainsalient parts of the aforesaid Neracher et al. application.

In the drawingsfA represents the internal combustion engine whichdrivesv through fluid coupling B and conventional typeof `friction mainclutch C to the speedv ratio transmission D whence the drive passesfrornoutput shaft 28 -f to drive the rear vehicle wheels' in the usualmanner. v

The engine crankshaft 2l carries the vaned fluid coupling impeller 22which in the Wellknown manner drives the lvaned runner 23 whence thedrive passes through hub 24 to clutch driving member 25. This memberthen-transmits the drive, when clutch C is engagedy as in- Fig. 2,through driven member 26`t0 Vthe transmissionl driving shaft '21carryingthe main drive 35 pinion28. Aclutch pedal 29 controls` clutch Csuch that'when'the driver-depresses this pedal', collar 39* isthrust-forward' to cause llevers 3l to release they clutch drivingpressure plate 32- clutching moveagainst springs' 33' thereby releasingthe'drive 40- b'etween runner 23y and-shaftl 21'. The" prima-ryfunctioniofthe` main clutch C isl to--ena'blethe' driver tomakefmanualshifts in transmission'D.-

Referring to the` transmission, pinion=28 isl inv constant mesh withgear tershaft` ."35Y through an overrunning'clutch" ofthe usual typesuch that' whenshaftZi drivesj in its usual clockwise'direction(lookingv from` front to rear) then clutch E will engage to lock^ gear34 to countershaft 35" whenever the gear 50" 34 tends to drive fasterthan the counter'shaft. However whenever this gear 34 tends'to rotateslower than the countershaft then clutch E'will automatically releasewhereby shaft 21, under certain conditions; may readily'dropitsv speedl5'5" while countershaft 35 continues to revolve.v

Countershaft 35 comprises cluster gears 36,

31 and 38 which respectively provide drives in rst, third and reverse.Freely rotatable on shaft are the rst and third driven' gears'394 and do40 respectively in constant mesh with countershaft gears 36 and31'. Ahub 4i" is splined on shaft 2D and carries therewith a manuallyshiftable sleeve 42 adapted to shiftvfrom theV Fig. 3v neutral positioneither rearwardly to clutch with 65 teeth 43 of gear 39 or elseforwardly lto clutch with teeth 44 of gear 4l). Sleeve 42 is operablyconnected to shift rail 45 adapted for operation by any suitable meansunder shifting control of the vehicle driver.

Shaft 20 alsocarries reverse driven gear 4t" fixed thereto. Areverse'idler gear 41' is suitably mounted so thatwhen reverse drive isdesired, idler 41 is shifted into meshwith gears 38-and 46. l

First, third andreverse speed ratio drivesand' 'it'K 0 else betweenthese teeth toallow' neutral are under manual shift control of thevehicle driver, the main clutch C being released by depressing pedal 29in shifting into any one of these drives.

First is obtained by shifting sleeve 42 to clutch with teeth 43, thedrive passing from engine A, through uid coupling B, clutch C and shaft21 to pinion 28 thence through gear 34 and clutch E to countershaft 35.-From the countershaft the drive is through gears 36, 39 and sleeve 42 toshaft 29.

Third is obtained by shifting sleeve 42 to clutch with teethv 44, thedrive passing from the engine to the countershaft 31 as before, thencethrough gears-31,40and sleeve 42 to shaft 2U.

Reverse is'obtained by shifting idler into mesh with gears 38, I46,lsleeve 42 being in neutral, the reversev drive passing" from the engineto the countershaft as before, thence through gears 0 38, 41 and 46 toshaft 20.

Slidablysplined'on teethl 48 carriedby" gear is the automatic clutching'sleeve: F-"Which,1 under certain conditions', is adapted 'to'shift'fI-l`wardly to clutch with teeth-49-'cariieduby pinion 28 thereby positivelyclutching' shaft 21 directlyi to gear 4G. This-sleeve-F is adaptedto'step-up the speed ratio drive fron'r'ist'tose'condan'dl from third tofourth whichf-is'a -direct drive speed ratio.l Control meansis-provided'which' limits clutching of sleeve F to approximatesynch'ronismwith teeth 49 and 'also to acondi-tion loflfen'ginc coast,sleeve F beingprevented-fromiclutchingv during that condition vknownasenginedriveias'* when the-engine is being' lspeeded upunder powerf-When'driving in first,- second"isObtainedbyi the driver releasing theusualv acceleratorpedal-l 5U thereby closing vthe engine throttle'valveandJl allowing the engine to Vrapidly coast down. When* this occurs, theengine alongwith shaft21, pin-A ion 28 and gear 34-allslow down'whileshaft-20'L along with gears 39 and 36 continue their speeds byaccommodation-of clutch E which-now over-'f runs. rI'heengine slowsAdown until teeth-49er@ I brought to `approximate synchronismiwithsleeve 34 which drives coun- 45*A F which thereupon automatically shiftsto clutclii with teeth'4`9 resulting'ina'tWo-vva'y'- drive-fori' secondasY follows: pinionY 28 throughI sleeve F to gear 49 thence throughgears 31;v 36" and 39i to sleeve 42 andA shaft' 20, the clutch Elvoverl" running. u

When driving in third, fourth" or directtisobtainedjust as for second bydriver release o'rthef'A accelerator pedal and resulting shiftof'sleeveill to clutch with teeth t9-when these parts-are syn--chronized'by reason of' the engine coas'tingfdownA from the drive inthird. Thedirectdrive'isa" two-way drive as follows: pinion 28Lthroughvl` sleeve F to gear' dilfthence directly through sleevel 42 toshaft 20, lclutch E overrunning'as before.l

Referring to Figs. 4 to 9" there is shown4 tli'e. blocking means forcontrolling clutching'shifti of sleeve F'so asv to` limit clutching'thereof't'o'l engine coasting and synchronous;relationshipof theclutching parts. Sleeve F isprovided witl'ia series ofv pairs of whatlmaygbey termed longardl short teeth 50, 5| certain of which may beYbridged or joined'together. Ak blocker ring 152i'isv provided withblocking teeth 53fwhich either li" in the path of forwardshift ofteetlrSU or 5i` or'" clutching shifty of sleeve F. Thus; blocker52'has", atfsuit'yable locations, a drive lug 54 engagedrin a slot55:"0'1"l gear 40. The blocker is urged underlightenergizing pressureoif'sprirvlgfV 56 intolconstant'- frictional engagement f at'r 5=1withgear' 49T so'V thatitl'e'f blocker tends to rotate with gear 49within the limits afforded by the travel of lug 54 circumferentially inslot 55.

During drive in first and third, the speed of shaft-21 exceeds the speedof gear 40 so that, if sleeve F is fully released, the parts will bepositioned as in Fig..5 wherein the blocker leads the sleeve F therebypositioning blocker teeth' 53 axially in alignment with the short teethIf now the sleeve F is urged forwardly itwill move to the Fig. 6position of drive blocking and will remain in this blocked position aslong as the engine drives the car in first or third.

If now the driver releases the accelerator pedal so that the engine maycoast down under accommodation of overrunning clutch E, while sleeve Fis urged forwardly, then when gear 49 is reduced in speed to that ofsleeve F slight further drop in speedof gear 49 for a fraction of varevolution below the speed of sleeve F will cause blocker 52 to rotateslightly relative to sleeve F until blocker teeth 53 strike theadjacentsides of long teeth 58 as in Fig. 7 thereby limiting furtherreduction in speed of theblocker relative to sleeve F. At this time thesleeve F is free to complete its forward clutching shift with teeth 49,as in Fig. 8, the blocker teeth 53 passing between adjacent long andshort teeth 50, 5|. With the sleeve F thus clutched during engine coast,a two-way drive is established in `second or fourth depending on whetherthe manually shiftable sleeve F was set for rst or third just prior tothe clutching shift of sleeve F.

In the event that sleeve F is urged forwardly from its Fig. 5 positionat a time when the gear 40 is rotating faster than pinion 28, then .theblocker 52 will lag behind the sleeve and will be blocked by engagementof long teeth 58 with the blocker teeth 53 as shown in Fig. 9. This isreferred to as the coast blocking condition. If now the engine isspeeded up by the driver depressing the accelerator pedal in the usualmanner, then the engine and blocker 52 rotate forwardly and blockerteeth 53 move over to the Fig. 6 drive blocking position thereby jumpingthe gap between teeth 58 and 5|. This is the primary reason forproviding the long and short teeth whereby sleeve F clutches only fromthe drive blocking condition followed by engine coast which protects theteeth and avoids harsh clutching effects on the passengers andtransmission mechanism. On accelerating the engine from the Fig. 9 coastblocking condition, the engine comes up to a speed limited by engagementof the overrunning clutch E for drivein either first or third dependingon the setting of the manually shiftable sleeve 42. Then on releasingthe accelerator pedal the sleeve F will synchronously clutch with teeth49 during coast to step-up the drive to either second or fourth asaforesaid.

. The transmission is provided with suitable prime mover means forcontrolling shift of sleeve F along with several control means.Referring particularly to Figs. 10 and 11 there is illustrated apressure uid operated motor G utilizing differential air pressure forits operation. For convenience this motor is arranged to operate by thevacuum in the intake manifold system of the engine under control` ofelectromagnetic means illustrated in the form of a solenoid H.

j Forward shift of sleeve F is effected, under control of motor G, byreason of a spring 58 xed at one end and exerting a pull on lever 59which is connected'to sleeve F through the cross-shaft 68 and shifteryoke 6|. Pivoted to the lower end of lever v59 is a follower rod 62guided in a support 63 and in the rubber sealing boot 64 carried bycylinder 65` which contains the diaphragm piston 66 urged in a directionto release sleeve F by a spring 61 which is much stronger than spring58. Diaphragm piston 66 is connected to a leader rod 68 which has a rearextension 69 aligned with rod 62.

Rod 68 has a'series of detents 10, 1| and 12, the latter cooperatingwith a latch 13 such that when vacuum is admitted to chamber 14 to causethe piston 66 and rod 68 to assume their Fig. 11 positions, latch 13under action of rat-trap spring 15 catches on the forward shoulder ofdetent 12 and holds the parts as in Fig. 11. At this time rod portion 69moves further than rod 62 by the amount of gap 16, a stop 11 acting onlever `59 limiting forward movement of sleeve F by spring l58.

In order to provide for release of sleeve F, it is desirable to provideSome means for momentarily relieving Vthe torque load at the teeth 49and sleeve F and in the present instance I have provided such means as asystem of grounding the distributor of the ignition system whereby theengine ignition may -be momentarily rendered ineffective therebyunloading the torque at sleeve F suciently to insure its release byspring 61. This ignition interrupting system is under control of aninterrupter switch 18 which is closedV by plunger 19 and ball 80whenever rod 69 moves between the Fig. 10 and Fig. ll positions byreason of the enlarged rod portion between detents 10, 1|. Detent 1| isso arranged that, with the parts as in Fig. 11 and sleeve F clutched,rod 68 may move rearwardly suiiciently to close gap 16 at thelost-motion between rod portion 69and rod 62, this movement causingswitch 18 to close and ground the ignition system whereupon spring 61may then cause further movement of rod 68 and rod 62 to release sleeveF, the switch 18 then opening by detent 10 to restore the ignitionsystem.

The vacuum supply to chamber 14 is under control of solenoid H whichcomprises an armature plunger 88 having valving parts 8|, 82. In Fig. 10the solenoid H is energized thereby raising plunger 8|! against spring83 to seat valve 82 and shut off the vacuum supply to chamber 14 and atthe same time unseat Valve 8| so as to vent this chamber through passage84, chamber 85 and vent passage 86. When the solenoid is de-energizedthen spring 83 lowers plunger 8|] thereby seating valve 8| to shut olfvent 86 and'open valve 82 as in Fig. 11 thereby opening chamber 14 tothe engine intake manifold K through passage 84, chamber 86', and pipe81.

A `vcertain lost motion is provided between plunger 88 and the inwardlybent nger 13 of latch 13 so that when the plunger moves downwardly thelatch may subsequently catch at detent 12 when vacuum operates piston66, the parts then remaining in the Fig. 1l position independently ofvacuum in chamber 14 until solenoid H is energized to release the latchand vent chamber 14.

It is deemed preferable to provide a speed control on the energizationof solenoid H so as to insure automatic release of sleeve F below apredetermined car speed and automatic engagementof sleeve F above apredetermined car speed. Whenever the car is in forward driving`condition the manual sleeve 42 is either shifted rearwardly to the lowrange orforwardly to :the high range so that by driving a governor .fromthe countershaft 35 it :is possible to .provlde'a speed control operatedproportionate to the speed of travel of thecar. Driven .fromcountershaft gear 88 is a governor J of any suitable type, this governoroperating a sleeve 89 .outwardly along its drive shaft 90 as the carspeed reaches a predetermined point, the break-away being under controlof a detent 9| if desired.

The sleeve 89 has a shoulder 92 engaged by the swinging switch .piece 93yof the governor switch 94. When'the car is stationary the de.- tent 9|is engaged and switch Bills-closed. SAs the car accelerates the governoreventually reaches its critical speed and detent 9| releases therebycausing switch 94 to open. As the car slows down, the governor spring 95restores the parts to the Fig. 10 position and by proportioning thevarious parts it is obvious .that switch 94 may be made to function atdesired speeds proportionate to car travel. As an example of onearrangement of governor operation and gearing arrangement, the governormay be made to'open switch 94 during car acceleration in first and thirdrespectively at approximately 7 and 15 M. P, H. (miles per hour), theswitch '94 closing on stopping the car in direct and second atapproximately 7 and 3 M. P. H. respectively.

I have provided suitable means to maintain control of the energizationof solenoid H and hence control on the operation of motor Gindependently of the normal control on these parts by the governorswitch 94. Ordinarily intransmission systems of this character, theignition switch is arranged in series with the circuit to the solenoid Hand governor switch 94 with the result that, in bringing the car to astop, if the driver prematurely shuts off the ignition switch, then eventhough the governor switch 94 closes to ordinarily (with the ignitionswitch closed) energize the solenoid, the solenoid circuit is broken andthe aforesaid diculties may result, in a manner hereinafter set forth.In order to avoid these difficulties llf have provided means, preferablyresponsive to operation of the engine where vacuum is employed tooperate motor G, to maintain the control on Athe solenoid under theaforesaid conditions, this means `operating even though the ignition isshut off andas long as the engine is running sulciently that vacuumcould operate piston G6 to the Fig. 11 latched position. One such means,by way of illustrating my invention, comprises what may be called avacuum switch L which is shunted around the ignition switch so as tocontrol the governor switch and solenoid circuit independently of theignition switch such that as long as there is an appreciable vacuum inthe intake manifold Kthen the solenoid will remain energizedindependently of the ignition switch. Whenever the engine is operatingthere will be a certain degree of vacuum in the intake manifold so thatmeans operating in response to manifold pressure conditions is therebyresponsive to engine operation.

The switch L is controlled by a movable conductor 96 carried by adiaphragm-91 which divides casing 9B into two chambers 99 and |00.Chamber 99 is in continuous communication at l! with manifold K, andchamber |00 isvented to Ethe-*atmosphere at |92. A light spring |03raises conductor `96 upwardly so as to open switch L when'the vacuum inmanifold K has fallen -so low that it would be ineffective 'to operatepiston 66. I

The secondary governor solenoid circuit. under control of switches-94and L in series, comprises ground |04 to switch94thence throughconductors |95, '|06 and |01 to solenoid H1 thence .by conductor |08 toswitch L, ammeter |09, battery Il!) and .ground In Fig. 10 I haveillustrated a portion of the, engine ignition Vcircuit which `extends'frombattery v|||l yand ammeter |99 to ignition switch |2 thence by wire|32 to coil |3 and by wire .|33 to distributer ||4.

The ignition grounding circuit for rendering the ignition momentarilyinoperative comprises a vgrounding conductor ||5 extending from theprimary terminal |34 of distrlbuter ||4 .tofthe ignition interrupterswitch y18, thence by .conf ductor ||6 to conductor |06 which has abranch ||1 extending to ground H8 under control of a switch ||9 called`the kickdownswitch because it is controlled by the accelerator pedal 50when fully depressed to eiect step-down in the transe mission speedratio.

The secondary kickdown solenoid circuitr extends from ground ||8 throughswitch ||9 and conductors ||1, |06 and |01 through solenoid' H andthence through switch L to ground Hijust as for the governor solenoidcircuit. Y The kickdown switch ||9 is preferably 'closed when the enginethrottle valve |20 (Fig. l) fully open. This may be accomplished byarranging the accelerator pedal 50 for a movement overtravelling. itswide open throttle position. Pedal 50foperates a link |2| so as to swingbell crank lever |22', |23 about its pivot |24. Lever armlZZ operateslink |25 which is connected to throttle valve lever |2`6through a lostmotion spring |21. Ordinarily this spring affords a solid connectionbetween link |25 and lever |26 but when pedal -50 is depressed to causelever |26 to engage stop |28 at wide open throttle, then furtherdepression of pedal 50 will cause finger |29 of lever arm |23 to throwarm |30 of switch ||9 upwardly thereby closing switch IIB, the spring|21 yielding to accommodate this overtravelling movement oftheaccelerator pedal. `When the pedal is released, thennger |3| restoresswitch 1|.9 to open the `kiclrdown solenoid circuit.

4The* ignition switch H2 comprises a 'swinging conductor l| pivoting at|36 and always elec-l trically connected by wire |31 to ammeter |09 andbattery H0. The-switch conductor |35'ha`s a main contact |38 which, whenthe switch is fvclosed as illustrated by solid lines, electricallyconnects wires |31 and |32. The switch conductor |35 also has anauxiliary contact |39 which, when the switch is closed, supplies curi-Yrent to the various accessories such as thejve# hicle, radio, heater,gasoline gauge, etc. As' an ex*- ample, the current is thus suppliedby'wire |40 and switch |4| to the grounded accessory l42. `Wlrenvtheswitch A| |2 is "open then contacts1|3`8 and |39 are no longerelectrically connectedto 'wires |32'and |49.

I-have incorporated a jumper conductor'wire |43 betweentheignitionswitch |'I2 (at the'current-delivery side) and conductor |08.For this purpose I utilize the auxiliary'contact |"3=9"for con'- trolingelectrical. connection between wires |31 and |98. With this arrangementthe switch 'L is, in effect, shunted around the ignition switch orvdisposed in parallel relation therewith s`o`that current from batterymay flow directly from battery ||0 and ammeter |09 through switch I25and wire |43 to Wire |08 through primary governor solenoid and kickdownsolenoid circuits just like the aforesaid corresponding secondarycircuits. The primary and secondary circuits are therefore identicalexcept that in the case of the primary circuits the switch L isby-passed or shunted.

In the operation of thernechanisrn, the car at standstill and with theignition switch H2 closed and the engine idling will cause the solenoidH to be energized as in Fig. through the primary governor solenoidcircuit because governor switch 94 is closed. Furthermore, vacuum inmanifold K will cause switch L to be closed thereby establishing thesecondary governor solenoid circuit. Cylinder 14 is vented and sleeve Fdisengaged. The driver shifts sleeve 42 to either the high or lowrangeand accelerates the car ordinarily above the critical speed or"governor J thereby causingzswitch 94 to open. As vacuum builds up in theengine intake manifold K, plunger 80 no w being lowered by spring B3because switch 94 is open,'piston '#56 will be operated by vacuumthereby moving rod 68 to its Fig. 11 latched position. As soon as thedriver allows the engine to'coast, sleeve F will engage teeth 49synchronously, to step-up the drive to either second or fourth althoughthe step-up will be delayed until engine coast thereby enabling drive inthe slower driving ratio of rst or third as long as desired. A

If the car is initially accelerated in first' above the governorcritical speed and the engine allowed to coast, then second willautomatically become operative. Then if the driver shifts sleeve 42forwardly to the high range, third will of course be skipped and fourthwill be obtained because sleeve F will remain engaged. Ordinarilyespecially where the car is equipped with a fiuid coupling B, the sleeve42 may be left in its high range and all starts and stops made withoutfurther shifting. 'Ihis is possible owing to slippage in the fluidcoupling when stopping the car for a traic light Iand is practicablebecause the fluid coupling allows high engine torque for favorable caracceleration and because governor J directs a downshift' on bringing thecar to rest. Thus there is automatically provided 'a favorabletorque-multiplying gearing for starting, as in third.

Whenever the car is driving in fourth or second above thegovernorcritical speed, a full depression of the accelerator pedal will causethe transmission to step-down tol third or rst, the transmission step-upback to fourth or second taking place on release of the acceleratorpedal with attendant synchronization of sleeve F with teeth 49.

When the accelerator pedal is fully depressed for the kickdown, switch II9 closes thereby energizing the kickdown solenoid circuits (bothprimary and secondary) and causing solenoid H to raise plunger 3l) andrelease latch 'I3 thereby venting chamber 74. At this time the sleeve Fis under driving torque from the engine operating under wide openthrottle. However, when latch I3 is released, spring 6'1 operates rod 68rearwardly suiciently to close gap IE thereby closing the interrupterswitch 'I8 and grounding the engine ignition system. This relieves thetorque at sleeve F and spring 6l operates to release the sleevewhereupon the ignition is restored at detent 'I0 and the engine quicklyspeeds up to engage overrunning clutch E for establishing the third orflrst driving ratio depending on the setting of sleeve 42 prior to thekickdown operation.

On bringing 'thel car to a stop when sleeve F is clutched as in fourthfor example, the vacuum switch vL insures release of sleeve F especiallyin the event that the engine ignition is turned off at switch I I2 priorto bringing the car to rest.

Heretofore, without the vacuum switch or the equivalent thereof, theignition switch I I2 was in series, as illustrated, with both thegovernor solenoid and the kickdown solenoid circuits with the resultthat ifthe car, when in fourth, was brought to rest by the vehiclecoasting against the engine, with the ignition switch open, then theengine would be driven as a pump by the car, and with the solenoidde-energized, the engine turning over would cause sufcient vacuum at thechamber 'I4 to cause piston 66 to operate and to latch as in Fig. l1even though the sleeve F is then released. Then on stopping the car aslight backward roll of the car would cause blocker 52 to move justenough to unblock the sleeve'and allow the latter to move forwardly byspring 53 and clutch with teeth 49. The effect is especially noticeableon stopping the car on an upgrade, such condition giving rise to thebackward roll and undesired clutching of` sleeve F-inthe stoppedposition of the car. Now with sleeve F'engaged and the gear shifter setfor high range-,.(sleeve 42 clutched with teeth 44) Where it is normallyleft until leaving the car, the backward roll produces a locked-upeifect in the transmission making it impossible to shift sleeve 42 outof its clutched position. This is occasioned by the car attempting toestablish drives in two different ratios in the transmission, one drivebeingfrom gear 40 directly vto pinion28 and the vother being' alsobetween pinion 95 and gear Il!!! but throughgearl 96,.clutch E and gearIBB. The result is tohold the car against movement and to load the-teethof sleeve 42 in the shifted position. Now if the driver attempts todrive the car forwardly he naturally closes the ignition switch to startthe engine but the engine will not start because the ignition systemvwill ground and the car remains stalled. The ignition grounds becauseunder the assumed conditions the rods 69 and 62 are positioned as inFig. 11 on stopping the car so that as soon as the ignition switch isclosed the solenoid H isV energized through the primary governorsolenoid circuit (and by the secondary governor solenoid circuit as soonas the engine is turned over by the starter) and rod 69 moves to take upgap 'ISthereby holding interrupter switch 'I8 closed because sleevev Fbeing loaded by backward roll tendency of the car cannot release byspring 61. Of course, if the car is stopped without rst turing off theignition then governor switch 94 closes and solenoid His energizedthereby maintaining chamber 'I4-vented and allowing spring 61 to releasesleeve F when the torque becomes very low as it does just before the carcomes to rest. The trouble heretofore arises therefore in allowing theVacuum to operate in chamber I4 as the car is brought to rest, as inturning off the ignitionsuch that the governor switch cannot establishits circuit to the solenoid and prevent latching of the piston. Somedrivers have a habit of turning oif the engine ignition when they areapproaching the point where they are going to park the car, allowing thecar to coast to a stop and the difficulties heretofore arise with somefrequency under such conditions.

By reason of my invention, I prevent the foregoing difiiculties arising.Assuming that the car is stopped in fourth and the ignition switch Il2is left closed as it ordinarily is, then, as the governor switch 94closes, the solenoid His raised and chamber 14 vented thereby insuringyrelease of sleeve F `as-before. Under such conditionsswitch L remainsclosed as the engine is running'and diaphragm- Blis operated by vacuumin manifold K. Now let it be assumed that thefcar is driving in fourthand the driver opens switch H2 and brings the car to rest 4on anupgrade, leaving sleeve 42 shifted forwardly. As the car approaches astop, theengine will not operate under its own power but willneverthless be driven through transmission D, cl-utch C'and fluidcoupling B so that it will act as a pump and'maintain vacuum in manifoldK. When thevvehicle thus drives the engine, rsuch condition' isordinarily referred to as coasting against the engine because the enginedoes not then drive thel vehicle. This vacuum maintains switch L closedand as the governor switch 94 closes on 'car deceleration, the solenoid3 His maintained energized `by the secondary governor solenoid circuit,chamber 'Mis maintained vented, and piston Sli isv prevented from'becoming latched. Furthermore, spring I 03- is very light vandw-illrespond to a slight degree of vacuum in ,l

the manifold so that when the vacuum nally falls to the point whereswitch L opens to dre-energize the solenoidH and allow plunger 80 vtolower, then thevacuum is not sufilcient to operate piston 66 toits'latched posi-tion. Therefore the car is lalj ways brought to a stop`with the sleeve F disengaged thus preventing the transmission lock-up,insuring against interruptor switch 18 undesirably grounding the eng-ineignition as the piston will be in the Fig. position, and insuring-thenext aoceleraton of the'car in 'a favorable torque-multiplying ratiowhich is third if'sleeve A42 is left in its position of forward shift.

While I have described the condi-tions attendant to stopping the "car infourth, it will be apparent 'that the same circumstances arise instopping the car in second-because in each instance the sleeve I'"v isclutched prior to slowing down the car to where the governor switch 94closes and in each instance sleever 4'2 is c-lutched for a forwarddrive.

Among the advantages of shunting the vacuum switch L around Itheignition switch are theY following:

When the driver approaches thevehicle to start the engi-ne, the instantthatrth'e ignition switch ll'Z-is closed preparatory `to enginestarting. solenoid H is thereby energized through the primarygovernorsolenoid circuit without having to wait untilthe engine turnsover tocreate vacuum for closingswitc'h L. This-has the advantagetherefore in `further safeguarding-the desired function of ysolenoid Hparticularly to insure energizing thev solenoid at the time of gettingthe engine started thereby insuring spring 'El directing or holdingIsleeve F in its Fig. 3 -position of release.

With my shunt switch arrangement, the system is also protected in theevent that the switch L sticksy in open position because solenoid H isthen under normal control of the `primary circuits although theprotection provided by switch L would, ofcourse, not'be'present.

Furthermore, my system does not require any material change in the usualwiring system cornprising the aforesaid series arrangement of ignitionswitch I |12, coil H, and switch 94 or lill. Switch L may be addedtherefore to the foregoing Aconventional arrangement.

-Still further, my switch shunt arrangement has the advantage that ifthe engine in starting tends to miss or "buck as sometimes happens incold weather, the solenoid H will nevertheless remain energized throughthe primary governor solenoid circuit regardless of fluctuations inswitch L due to vacuum fluctuation and resulting closing and opening ofthe secondary governor solenoid circuit.

I claim:

1. In a power transmission for driving a motor vehicle having an engineprovided with an ignition system; an ignition control switch adaptedwhen closed to render the ignition system operative and when open torender the ignition system inoperative; a speed ratio varyingtransmission; transmission control means including a motor operable tocontrol said transmission for step-up and step-down change'in the speedratio drive from the engine to-the vehicle; electrically operated'meansfor controlling operation of said motor having a control circuittherefor including said ignition switch; a second switch connected insaid circuit in parallel with said ignition switch; and means comprisinga vdineren-tial pressure actuated member operable independently of saidignition system for controlling said second switch whereby saidcontrolcircuit may be maintained in energized condition'when saidignition switch is open.

2. In a power transmission for driving-a motor vehicle having an engineprovided with an ignition system; an ignition control switch adaptedwhen closed to render the ignitionsystem operative' and'when open torender the ignition system inoperative; a speed ratio varyingtransmission; transmission control means including a differentialpressure fluid motor operable t0 Acontrol said transmission for step-upland step-down change in the speed ratio drive from the engineto thevehicle; a source of differential pressure iluid for actuating saidmotor; electrically operated means for controlling operation of saidmotor having a control circuit therefor including said ignition Iswitch;a second switch connected in said circuit in parallel with said ignitionswitch; vand means operated by said pressure source for closing saidsecond switch whereby said control circuit may be maintained inenergized condition when said ignition switch is open.

3. A power transmission for'driving a motor vehicle having an engineprovided with an ignition system; an ignition control switch adaptedwhen closed to render the ignition system operative and when open torender-the ignition system inoperative; a speed ratio varyingtransmission; transmission control means including a motor operable tocontrol said transmission for stepup and step-down change in the speedratio drive from the engine to the vehicle; electrically controlledmeans including said ignition control switch for controlling yoperationof said motor; means comprising a switch shimted around said ignitioncontrol switch for controlling `energization of said electricallycontrolled means; and means operating automatically in response tovehicle coast against the engine, when said ignition control switch isopen, for effecting operation of said shunted switch.

4. In a power transmission for driving a motor vehicle having an engineprovided with an ignition system; an ignition control switch adaptedwhen closed to render Vthe ignition system operative and when Aopen torender lthe ignition system inoperative; a speed ratio varyingvtransmission; transmission control means .including'a differentialpressure fluid' motor operable to control said transmission for step-upand step-down change in the speed ratio drive from the engine to thevehicle; a source of differential pressure iiuid for actuating saidmotor; electrically operated means for controlling operation of saidmotor; and means shunted around said ignition control switch andoperated by said pressure source, when said ignition control switch isopen, for controlling energization of said electrically operated means.

5. In a power transmission for driving a motor vehicle having an engineprovided with an ignition system; an ignition control switch adaptedwhen closed to render the ignition system operative and when open torender the ignition system inoperative; a speed ratio varyingtransmission; transmission control means including a motor operable tocontrol said transmission for step-up and step-down change in the speedratio drive from the engine to the vehicle; electrically controlledmeans for controlling operation of said motor; means shunted around saidignition control switch for controlling energization of saidelectrically controlledmeans; and means operating automatically inresponse to Vehiclev coast against the engine, when said ignitioncontrol switch is open, for eiecting operation of said shunted means. Y

6. A power transmission for driving a motor vehicle having an engineprovided with an ignition system; an ignition control switch adaptedwhen closed to render the ignition system operative and when opened torender the ignition system inoperative; a speed ratio varyingtransmission; transmission control means including a motor operable tocontrol said transmission for step-up and step-down change in the speedratio drive from the engine to the vehicle; electrically operating meansfor controlling operation of said transmission control means; a controlcircuit, including said ignition control switch, for said electricallyoperating means; switch means, connected in said circuit in parallelwith said ignition control switch, for controlling energization of saidelectrically operating means; and means operable in response tooperation of the engine by reason of the engine being driven by thevehicle, when said ignition control switch is open, for effectingoperation of said switch means.

'7. A power transmission according to claim 6; said control circuitincluding means operably responsive to predetermined vehicle drivingspeed for controlling energization of said electrically operating meansin conjunction with said switch means.

8. A power transmission according to claim 6; a speed-responsive switchinterposed in said control circuit; and means for opening and closingsaid speed-responsive switch in response to predetermined driving speedof the vehicle.

9. In a power transmission according to claim 4 wherein, said source ofdifferential pressure fiuid comprises the partial vacuum in the intakesystem of the engine.

10. In a power transmission according to claim 5 wherein, said source ofdierential pressure fluid comprises the partial vacuum in the intakesystem of the engine.

ll. In a power transmission for driving a motor vehicle having an engineprovided with an ignition system; an ignition control switch adaptedwhen closed to render the ignition system operative and when opened torender the ignition system inoperative; a speed ratio varyingtransmission; transmission control means including a motor operable tocontrol said transmission for step-up and step-down change in the speedratio drive from the engine to the vehicle; electromagnetic means forcontrolling operation of said motor; a control circuit, including saidignition control switch, for said electromagnetic means; switch means,connected in said circuit in parallel with said ignition control switch,for controlling energization of said electromagnetic means; and meansoperating automatically in response to vehicle coast against the engine,when said ignition control switch is open, for controlling operation ofsaid switch means.

12. A power transmission for driving a motor vehicle having an engineprovided with an ignition system and an intake system; an ignitioncontrol switch adapted when closed to render the ignition systemoperative and when opened to render the ignition system inoperative; aspeed ratio varying transmission; transmission control means including amotor operable to control said transmission for step-up and step-downchange in the speed ratio drive from the engine to the vehicle;electrically operating means for controlling operation of saidtransmission control means; a control circuit, including said ignitioncontrol switch, for said electrically operating means; and switch means,connected in said circuit in parallel with said ignition control switch,utilizing partial vacuum in said engine intake system when said ignitioncontrol switch is open for controlling energization of said electricallyoperating means.

13. A power transmission system for driving a motor vehicle having anengine provided with an ignition system; an ignition control switch; achange speed transmission; electrically operable control means for saidtransmission; a control circuit, including said ignition control switch,for said electrically operable control means, and a pressuredifferential operated switch, connected in said control circuit inparallel with said ignition control switch, for controlling energizationof said electrically operable control means independently of saidignition control switch.

14. A control system for an engine driven change speed transmissionhaving an electrically energizable control device therefor; a controlcircuit, including an engine ignition control switch, for said device;automatically operating switch means in said circuit paralleling saidignition control switch so constructed and arranged as to controlenergization of said device when said ignition control switch is open,said'switch means comprising a differential pressure operated switchcontact member; and conduit means for subjecting said member to theintake system of the engine.

WILLIAM T. DUNN.

